Conversion of Red Muds into Pozzolans

1991 ◽  
Vol 245 ◽  
Author(s):  
Jean Pera
Keyword(s):  
Red Mud ◽  
Mineralogical Composition ◽  
Waste Materials ◽  
Strength Development ◽  
Blended Cements ◽  
Temperature Range ◽  
Lime Consumption ◽  
Red Muds ◽  
Mineralogical Compositions

ABSTRACTRed muds are waste materials obtained from the aluminium extraction industry. They consist mainly of clays, aluminium and iron hydrated oxides. Three muds were studied; they differed in chemical and mineralogical compositions. They were converted into reactive pozzolans by calcination in the temperature range 600–800°C for five hours. Pozzolanicity was investigated on calcined red mud-OPC mixes studying strength development and lime consumption as evaluated by DTA. The nature of hydrates formed during hardening was also identified.The mineralogical composition of the mud is the most important factor affecting its pozzolanicity. Blended cements containing 30% calcined red mud develop significant strengths.

scholarly journals Strength Development in Bio Mineralised Steelslag Bricks using Micp Process

2020 ◽  
Vol 9 (4) ◽  
pp. 2975-2980
Keyword(s):  
Steel Slag ◽  
Mineralogical Composition ◽  
Waste Materials ◽  
Firing Process ◽  
Strength Development ◽  
Composition Analysis ◽  
Calcium Carbonate Precipitation ◽  
Paper Mills ◽  
Carbonation Process ◽  
Steel Industries

Steel slag annual production in India is about 12 million tonnes per annum. Steel slag is one of the industrial residue came out from steel industries. The amount of steel slag produced from different steel industries is 150-200kg per tonnes of steel produced These steel slag is dumped in land and pollute the environment. Paper mills produce the large amount of lime sludge is about 5 lakh tonnes per annum. These steel slag used as binder material and coarse aggregate also in different sieve sizes. These both steel slag and lime material contains large amount of calcium mineral compared than other waste materials. The conventional burnt clay brick manufacturing firing process develops the 750 million tonnes of co2 emissions per year. The Bio mineralised steel slag bricks developed by using these waste materials and bacillus bacteria. These microbes generates the calcium carbonate precipitation in the steel slag bricks. The strength development of these BMSS bricks were achieved by addition of NBU medium supply and carbonation process. The scanning electron microscope (SEM), mineralogical composition analysis, X-ray diffraction analysis, compressive strength and water absorption test are conducted to support the strength development in bio mineralised steel slag bricks.

The Effect on Cement Mortar and Concrete by Admixture of Spray Drying Absorption Products

1989 ◽  
Vol 178 ◽  
Author(s):  
Kirsten G. Jeppesen
Keyword(s):  
Grain Size ◽  
Fly Ash ◽  
Cement Mortar ◽  
Setting Time ◽  
Mineralogical Composition ◽  
Cement Clinker ◽  
Strength Development ◽  
Fall Meeting ◽  
Freeze Thaw ◽  
Spray Dried

AbstractSpray dried absorption products (SDA) having special characteristics are used as substitutes for cement in the preparation of mortars; the qualities of the resulting mixed mortars are described. Conditions are described for mortar mixes, data for which were presented at the MRS Fall Meeting 1987.The influence of the composition of the SDA on water requirement and setting time has been studied. A full scale project involving 3 precast, reinforced concrete front-elements containing 20 and 30 wt.% SDA is described. Strength development, mineralogical composition and corrosion were monitored for two years.A non-standard freeze-thaw experiment was performed which compares mortars containing SDA and fly ash (FA) and also shows the effect of superplasticizer.The possibility of improving the SDA by grinding has been tested and a limited improvement has been found. The strength of the mixed mortars seems slightly influenced by the grain size of SDAGypsum (CaSO4·2H2O), synthetic calcium-sulphite (CaSO3·½H2O) and 2 SDAs have been used as retarders for cement clinker. Mortar test prisms have been cast and comparative strengths after curing for 3 years are reported

scholarly journals MATHEMATICAL MODELING OF LEACHING PROCESS OF RED MUD IN ORDER TO OBTAIN THE KINETICS PARAMETERS

2015 ◽  
Vol 14 (2) ◽  
pp. 90 ◽  
Author(s):  
K. L. M. Dos Passos ◽  
B. M. Viegas ◽  
E. N. Macêdo ◽  
J. A. S. Souza ◽  
E. M. Magalhães
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Red Mud ◽  
Mineralogical Composition ◽  
Raw Material ◽  
Data Conversion ◽  
Kinetics Parameters ◽  
Leaching Process ◽  
Iron Leaching ◽  
The Mathematical Model

The use of the waste of the Bayer process, red mud, is due to its chemical and mineralogical composition that shows a material rich in oxides of iron, titanium and aluminum. Some studies conducted show that this waste can be applied as a source of alternative raw material for concentration and subsequent recovery of titanium compounds from an iron leaching process, which is present in higher amounts, about 30% by weight. To obtain a greater understanding about the leaching kinetics, the information of the kinetic data of this process is very important. In this context, the main objective of this work is the development of a mathematical model that is able to fit the experimental data (conversion / extraction iron, titanium and aluminum) of the leaching process by which is possible to obtain the main kinetic parameters such as the activation energy and the velocity of chemical reactions as well as the controlling step of the process. The development of the mathematical model was based on the model of core decreasing. The obtained model system of ordinary differential equations was able to fit the experimental data obtained from the leaching process, enabling the determination of the controlling step, the rate constants and the activation energies of the leaching process.

scholarly journals Influence Of Volcanic Scoria On Mechanical Strength, Chemical Resistance And Drying Shrinkage Of Mortars

2014 ◽  
Vol 61 (3) ◽  
pp. 143-150 ◽  
Author(s):  
A. Al-Swaidani ◽  
S. Aliyan ◽  
N. Adarnaly ◽  
B. Hanna ◽  
E. Dyab
Keyword(s):  
Mechanical Strength ◽  
Sulphuric Acid ◽  
Chemical Resistance ◽  
Control Sample ◽  
Acid Resistance ◽  
Drying Shrinkage ◽  
Strength Development ◽  
Acid Solutions ◽  
Test Results ◽  
Blended Cements

Abstract In the study, three types of cement have been prepared; one CEM I type (the control sample) and two blended cements: CEM II/A-P and CEM II/B-P (EN 197-1), each of them with three replacement levels of volcanic scoria: (10 %, 15 %, 20 % wt.) and (25 %, 30 %, 35 % wt.), respectively. Strength development of mortars has been investigated at 2, 7, 28 and 90 days curing. Evaluation of chemical resistance of mortars containing scoria-based cements has been investigated through exposure to 5 % sulphate and 5 % sulphuric acid solutions in accordance with ASTM C1012 & ASTM 267, respectively. Drying shrinkage has been evaluated in accordance with ASTM C596. Test results showed that at early ages, the mortars containing CEM II/B-P binders had strengths much lower than that of the control mortar. However, at 90 days curing, the strengths were comparable to the control mortar. In addition, the increase of scoria significantly improved the sulphate resistance of mortars. Further, an increase in scoria addition improved the sulphuric acid resistance of mortar, especially at the early days of exposure. The results of drying shrinkage revealed that the CEM II/B-P mortar bars exhibited a greater contraction when compared to the control mortar, especially at early ages. However, drying shrinkage of mortars was not influenced much at longer times.

Characterization of a Red Mud and a Clay Body for Ceramic Fabrication

2014 ◽  
Vol 798-799 ◽  
pp. 514-519 ◽  
Author(s):  
Michelle Pereira Babisk ◽  
Thalissa Pizetta Altoé ◽  
Henrique Junio de Oliveira Lopes ◽  
Ulisses Soares do Prado ◽  
Monica Castoldi Borlini Gadioli ◽  
...  
Keyword(s):  
Red Mud ◽  
Mineralogical Composition ◽  
Processing Plants ◽  
Clay Matrix ◽  
Clay Body ◽  
Clay Ceramics ◽  
Red Ceramics ◽  
Ceramic Clay

Red mud is a specific term applied for a residue generated during the processing of aluminum ores, mainly bauxite in the Bayer process, to produce alumina (Al2O3). In several countries where bauxite is mined and processed, distinct red muds are generated in ever growing amounts and becoming an environmental problem. This problem is also affecting the large bauxite processing plants in Brazil and a possible solution for the red mud is its addition to clay ceramics. Before an industrial scale addition is implanted, the specific red mud needs to be characterized for compatible behavior with the ceramic clay matrix. Therefore, the objective of the present work was to characterize a red mud generated in Brazil for an eventual addition to clay ceramic. This was conducted through the determination of density, chemical and mineralogical composition as well as size distribution and microscopic observation of particles. The results indicated that the specific red mud investigated is compatible with clays and has a potential for addition in common red ceramics.

Development of Red Mud Coated Catalytic Filter for NOx Removal in the High Temperature Range of 300–450 °C

2019 ◽  
Vol 150 (3) ◽  
pp. 702-712 ◽  
Author(s):  
Lin Huangfu ◽  
Abdullahi Abubakar ◽  
Changming Li ◽  
Yunjia Li ◽  
Chao Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Red Mud ◽  
Nox Removal ◽  
High Temperature Range ◽  
Temperature Range ◽  
Catalytic Filter

scholarly journals Physicochemical and Microstructural Properties of Red Muds under Acidic and Alkaline Conditions

2020 ◽  
Vol 10 (9) ◽  
pp. 2993
Author(s):  
Qingke Nie ◽  
Youdong Li ◽  
Guohui Wang ◽  
Bing Bai
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Red Mud ◽  
Ph Value ◽  
Soil Layer ◽  
Microstructural Properties ◽  
Naoh Solution ◽  
Red Muds ◽  
Hcl Solution

The main purpose of this study was to characterize the mineral and chemical composition of typical red muds in China. Changes in the physicochemical and microstructural properties of red muds collected from the Shanxi and Shandong provinces were investigated after they were immersed in an alkaline NaOH or an acidic HCl solution for 7, 28, and 120 days. The results showed that red mud has a high cation exchange capacity and active physicochemical properties, which can be closely related to its extremely high alkalinity and complex microstructure. The neutralization of red mud with the HCl solution results in the release of Na+ from the red mud particles into the leachate and can effectively decrease the pH value of the filtrate. The neutralization process can result in a significant decrease in the liquid limit, plastic limit and plasticity index, whereas the opposite was observed for the different parameters after the addition of the NaOH solution. In this sense, acid neutralization can significantly improve the cementation property of the red mud. This result will increase the water permeability of the acid-treated soil layer and improve the growth ability of plants. The specific surface area of red mud immersed in the NaOH solution decreased, whereas the specific surface area of red mud immersed in the HCl solution increased. This study contributes to our understanding of red mud properties after the red mud has been subjected to acidic and alkaline treatments, and the results can provide insights into the safe disposal of red mud.

scholarly journals SHRINKAGE OF VARIOUS TYPES OF PORTLAND CLINKER-BASED CEMENTS WITH RESPECT TO THEIR HYDRATION DEGREE

2020 ◽  
Vol 60 (2) ◽  
pp. 88-97 ◽  
Author(s):  
Vendula Davidová ◽  
Pavel Reiterman
Keyword(s):  
Previous History ◽  
Blended Cement ◽  
Heat Evolution ◽  
Experimental Program ◽  
Strength Development ◽  
Contact Method ◽  
Volume Changes ◽  
Hydration Degree ◽  
Suitable Material ◽  
Blended Cements

The volume changes of cement based composites are significantly exhibited in the hardening process. Initial phases of the hardening are complemented by the expansion due to the heat evolution that is subsequently alternated by the shrinkage. Both could cause a crack initiation. It is evident that ultimate volume changes of cement based composites are a complex process, because the final shrinkage is determined by the binder used, exposition and also by the previous history. The paper focuses on the evaluation of the main types of cements based on the Portland clinker by using a conventional procedure for the determination of the shrinkage on the standard cements mortars. These mortars were exposed to drying after 1 and 3 days of curing, related to the actual degree of hydration, which was estimated on the basis of compressive strength development. The hydration process was additionally monitored using thermogravimetry on the accompanying paste specimens during one year. The performed experimental program confirmed the essential sense of the curing regime especially for blended cement systems, which exhibited very low values of the hydration degree at applied curing intervals. Despite the slightly higher values of shrinkage of blended cements, the obtained results signalize the crucial effect of prolonged curing for these types of binders. The conclusion highlighted the necessity of taking into consideration the hydration degree during cement testing by using the conventional contact method. Otherwise, the simple interpretation leads to an overestimation of the less-suitable material solution.

scholarly journals A mineralogical investigation of some Gold Coast soils.

1955 ◽  
Vol 3 (2) ◽  
pp. 127-134
Author(s):  
R. Hamilton
Keyword(s):  
Mineralogical Composition ◽  
Gold Coast ◽  
Mineralogical Investigation ◽  
Mineralogical Compositions

The mineralogical compositions of five types of melanites (alkaline, black heavy clays derived from a basic hornblende gneiss) and of alluvial fluviomarine soils (alluvites) from the dry savannah plains east of Accra and of two different groups of brightly coloured soils (rubrites) from the forested hills in Ashanti are tabulated. The ages and transportation of the soils are deduced from their mineralogical composition. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Physical Characterization and Durability of Blended Cements Based on Brick Powder

2020 ◽  
Vol 30 (3) ◽  
pp. 201-213
Author(s):  
Ghania Nigri ◽  
Yacine Cherait ◽  
Soraya Nigri
Keyword(s):  
Mechanical Properties ◽  
Sulfuric Acid ◽  
Research Work ◽  
Blended Cement ◽  
Waste Materials ◽  
Partial Substitution ◽  
Blended Cements ◽  
Brick Powder ◽  
Crushed Brick ◽  
Durability Performance

Abstract This research work discusses both the physical and durability characteristics of newly blended cement containing waste crushed brick. This waste is used as a partial substitution for clinker in cement. Thus, blended cements are obtained by grinding and homogenizing clinker, waste brick, and gypsum. Four compositions containing 0%, 10%, 20%, and 30% of waste materials were prepared and submitted to various characterization tests. The introduction of brick powder improved the physical characteristics, therefore; it improved the mechanical properties and durability performance of the new cement compared to the reference, prepared with 0% addition. More particularly, it resisted sulfuric acid (H2SO4) attack after fixation of portlandite by pozzolan.

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